The sentence you're objecting to isn't claiming that US healthcare is a completely free market (which, as you note, would be an unbelievably ignorant view to hold... literally unbelievably). It's claiming that certain failures of the fairly-free US system already illustrate the sorts of failures that would plague a free(er) system.

You may or may not agree with that conclusion, but it's a far more plausible view for someone to hold than what you seem to have thought the original poster meant.